This invention relates in general to a shift lever assembly for use with a manually operated transmission. In particular, this invention relates to an improved structure for such a shift lever assembly having a noise and vibration damper that reduces the amount of noise and vibration that is transmitted from the engine and the transmission into the driver compartment, and further that protects and conceals one or more lines that extend from a shift knob supported on an upper end of the shift lever assembly to the transmission.
In most vehicles, a transmission is provided in a drive train between the engine and the driven wheels. As is well known, the transmission includes a plurality of gears that are selectively engaged to provide a plurality of speed reduction gear ratios between an input shaft and an output shaft of the transmission. A control member (such as a stub shaft) is provided within the transmission and is adapted to be moved by a driver of the vehicle throughout a plurality of gear ratio positions for selecting and engaging the desired speed reduction between the input shaft and the output shaft. As a result, acceleration and deceleration of the vehicle can be achieved in a smooth and efficient manner.
In many smaller vehicles, such as automobiles, the transmission functions automatically to move the control member without any intervention by the driver of the vehicle. However, such an automatic transmission is typically not used in larger vehicles, such as trucks, because of the increased size and expense. Such vehicles are, therefore, often provided with a manually operable transmission, where the shifting of the control member is accomplished by physical movement of the control member by the vehicle driver.
In order to shift the control member between the gear ratio positions in a manual transmission, a shift lever assembly is generally provided. A lower end of the shift lever assembly extends downwardly into engagement with an upper end of the control member. The upper end of the shift lever assembly extends upwardly into a drive compartment of the vehicle, where it is convenient for the vehicle driver to grasp and manipulate it. Thus, when the upper end of the shift lever assembly is moved by the vehicle driver, the lower end thereof (as well as the control member connected thereto) are also moved. By properly moving the shift lever assembly, the vehicle driver may position the control member of the transmission to select and engage any one of the plurality of gear ratios for use.
When the vehicle is operated, it has been found that the engine, transmission, and other components of the drive train of the vehicle vibrate to a certain extent. All of such vibrations can be sensed by the vehicle driver as undesirable noise. To reduce the amount of this undesirable noise, the driver compartment of the vehicle is typically lined with an acoustical insulation material. Unfortunately, the shift lever assembly extends upwardly from the transmission into the driver compartment for convenient use. As a result, the shift lever assembly transmits these vibrations into the driver compartment, thereby by largely defeating the purpose of the acoustical insulation material.
To address this, it is known to provide the shift lever assembly with a noise and vibration dampening mechanism. Such noise and vibration dampening mechanisms are designed to reduce the amount of noise and vibration that is transmitted from the engine and transmission through the shift lever assembly to the driver compartment of the vehicle. A typical noise and vibration dampening mechanism includes one or more elastomeric damping members disposed within a cylindrical housing. A lower shift lever member has a lower end that is connected to the upper end of the control member of the transmission and an upper end that is secured to the noise and vibration dampening mechanism. An upper shift lever member has a lower end that is secured to the noise and vibration dampening mechanism. The noise and vibration dampening mechanism thereby provides a mechanical connection between the lower shift lever member and the upper shift lever member, which reduces the amount of noise and vibration that is transmitted from the engine and transmission through the shift lever assembly to the driver compartment of the vehicle.
Although known noise and vibration dampening mechanisms have functioned satisfactorily, there is a need for an improved shift lever assembly having a noise and vibration dampening mechanism that not only reduces the amount of noise and vibration that is transmitted from the engine and the transmission into the driver compartment, but further protects and conceals one or more lines that extend from a shift knob supported on an upper end of the shift lever assembly to the transmission.